Use of compolymer containing alkylene oxide units, as an additive in detergents and cleansers

ABSTRACT

Use of copolymers containing alkylene oxide units which comprise (a) 50 to 93 mol % of acrylic acid and/or a water-soluble salt of acrylic acid, (b) 5 to 30 mol % of methacrylic acid and/or a water-soluble salt of methacrylic acid and 
 
(c) 2 to 20 mol % of at least one nonionic monomer of formula I  
                 
in which the variables have the following meanings: 
         R 1  is hydrogen or methyl;    R 2  is a chemical bond or unbranched or branched C 1 -C 6 -alkylene;    R 3  are identical or different unbranched or branched C 2 -C 4 -alkylene radicals;    R 4  is unbranched or branched C 1 -C 6 -alkyl; n is 3 to 50, in random or block copolymerized form, as additive for detergents and cleaners.

The present invention relates to the-use of copolymers containingalkylene oxide units which comprise

-   (a) 50 to 93 mol % of acrylic acid and/or a water-soluble salt of    acrylic acid,-   (b) 5 to 30 mol % of methacrylic acid and/or a water-soluble salt of    methacrylic acid    -   and-   (c) 2 to 20 mol % of at least one nonionic monomer of formula I    in which the variables have the following meanings:    -   R¹ is hydrogen or methyl;    -   R² is a chemical bond or unbranched or branched C₁-C₆-alkylene;    -   R³ are identical or different unbranched or branched        C₂-C₄-alkylene radicals;    -   R⁴ is unbranched or branched C₁-C₆-alkyl;    -   n is 3 to 50,        in random or block copolymerized form, as additive for        detergents and cleaners.

The invention further relates to detergents and cleaners which comprisethese copolymers as deposit-inhibiting additive.

In the case of machine dishwashing, the ware should be obtained in aresidue-free cleaned state with a flawlessly gleaming surface, for whicha detergent, a rinse aid and regenerating salt for water softeningusually have to be used.

The “2 in 1” dishwashing detergents on the market comprise, in additionto the detergent for removing the soilings on the ware, integratedclear-rinse surfactants which, during the clear-rinse and dryingoperation, ensure flat water run-off on the ware, thus preventing limeand water marks. The topping-up of a rinse aid is no longer requiredwith the use of these products.

Modern machine dishwashing detergents, “3 in 1” detergents, are intendedto combine the three functions of the detergent, the rinse aid and thewater softening in a single detergent formulation, meaning that thetopping-up of salt for water hardnesses from 1 to 3 also becomessuperfluous for the consumer. To bind the hardness-forming calcium andmagnesium ions, sodium tripolyphosphate is usually added to thesedetergents. However, these in turn result in calcium and magnesiumphosphate deposits on the ware.

EP-A-324 568 describes water-soluble copolymers for detergents andcleaners which are obtained by polymerization of acrylic acid,methacrylic acid and alkoxypolyethylene glycol methacrylates which havea long-chain alkoxy radical and/or a long-chain polyethylene glycolblock in the presence of isopropanol. The alkoxypolyethylene glycolmethacrylate fraction of these copolymers is <1 mol %.

According to JP-A-1991/185184, it is possible to use copolymers based onat least one monomer from the group consisting of maleic acid, acrylicacid and methacrylic acid and an optionally methoxy- or ethoxylatedpolyethylene glycol (meth)acrylate as further monomer, which have anaverage molecular weight M_(w) of from 1 000 to 10 000, for thedesizing, cleaning, bleaching and dyeing of natural and syntheticfibers. Specifically disclosed are copolymers of acrylic acid andmethoxypolyethylene glycol methacrylate.

JP-A-2000/24691 describes copolymers of unsaturated carboxylic acids andmonomers containing polyalkylene oxide units with average molecularweights M_(w) of >50 000 to 3 000 000 as agents against scale, based inparticular on silicates., in water cycles, e.g. cooling systems.Specifically disclosed are again only copolymers of acrylic acid andmethoxypolyethylene glycol methacrylate.

It is an object of the present invention to remedy the problemsdescribed above and to provide an additive which can be usedadvantageously especially in multifunctional cleaners and at the sametime, in particular, exhibits a deposit-inhibiting action.

We have found that this object is achieved by the use of copolymerscontaining alkylene oxide units which comprise

-   (a) 50 to 93 mol % of acrylic acid and/or a water-soluble salt of    acrylic acid,-   (b) 5 to 30 mol % of methacrylic acid and/or a water-soluble salt of    methacrylic acid    -   and-   (c) 2 to 20 mol % of at least one nonionic monomer of formula I    in which the variables have the following meanings:-   R¹ is hydrogen or methyl;-   R² is a chemical bond or unbranched or branched C₁-C₆-alkylene;-   R³ are identical or different unbranched or branched C₂-C₄-alkylene    radicals;-   R⁴ is unbranched or branched C₁-C₆-alkyl;-   n is 3 to 50,    in random or block copolymerized form, as additive for detergents    and cleaners.

We have also found detergents and cleaners which comprise the copolymerscontaining alkylene oxide units as deposit-inhibiting additive.

The copolymers containing alkylene oxide units comprise, ascopolymerized components (a) and (b), acrylic acid or methacrylic acidand/or water-soluble salts of these acids, in particular the alkalimetal salts, such as potassium and primarily sodium salts, and ammoniumsalts.

The proportion of acrylic acid (a) in the copolymers to be usedaccording to the invention is 50 to 93 mol %, preferably 65 to 85 mol %and particularly preferably 65 to 75 mol %.

Methacrylic acid (b) is present in the copolymers to be used accordingto the invention in an amount of from 5 to 30 mol %, preferably in anamount of from 10 to 25 mol % and especially in an amount of from 15 to25 mol %.

The copolymers comprise, as component (c), nonionic monomers of theformula I

in which the variables have the following meanings:

-   R¹ is hydrogen or preferably methyl;-   R² is unbranched or branched C₁-C₆-alkylene or preferably a chemical    bond;-   R³ is identical or different unbranched or branched C₂-C₄-alkylene    radicals, primarily C₂-C₃-alkylene radicals, in particular ethylene;-   R⁴ is unbranched or branched C₁-C₆-alkyl, preferably C₁-C₂-alkyl;-   n is 3 to 50, preferably 5 to 40, particularly preferably 10 to 30.

Particularly suitable examples of the monomers II which may be mentionedare: methoxypolyethylene glycol(meth)acrylate, methoxypolypropyleneglycol(meth)acrylate, methoxypolybutylene glycol(meth)acrylate,methoxypoly(propylene oxide-co-ethylene oxide)(meth)acrylate,ethoxypolyethylene glycol(meth)acrylate, ethoxypolypropyleneglycol(meth)acrylate, ethoxypolybutylene glycol(meth)acrylate andethoxypoly(propylene oxide-co-ethylene oxide)(meth)acrylate, wheremethoxypolyethylene glycol(meth)acrylate and methoxypolypropyleneglycol(meth)acrylate are preferred and methoxypolyethylene glycolmethacrylate is particularly preferred.

The polyalkylene glycols contain here 3 to 50, in particular 5 to 40 andespecially 10 to 30, alkylene oxide units.

The proportion of the nonionic monomers (c) in the copolymers to be usedaccording to the invention is 2 to 20 mol %, preferably 5 to 15 mol %and especially 5 to 10 mol %.

The copolymers to be used according to the invention usually have anaverage molecular weight M_(w) of from 3 000 to 50 000, preferably from10 000 to 30 000 and particularly preferably from 15 000 to 25 000.

The K value of the copolymers is usually 15 to 40, in particular 20 to35, especially 27 to 30 (measured in 1% strength by weight aqueoussolution at 25° C., in accordance with H. Fikentscher, Cellulose-Chemie,vol. 13, pp. 58-64 and 71-74 (1932)).

The copolymers to be used according to the invention can be prepared byfree radical polymerization of the monomers. In this connection, it ispossible to work in accordance with any known free radicalpolymerization process. In addition to bulk polymerization, mention maybe made in particular of the processes of solution polymerization andemulsion polymerization, preference being given to solutionpolymerization.

The polymerization is preferably carried out in water as solvent. Itcan, however, also be carried out in alcoholic solvents, in particularC₁-C₄-alcohols, such as methanol, ethanol and isopropanol, or mixturesof these solvents with water.

Suitable polymerization initiators are compounds which either decomposethermally or photochemically (photoinitiators) to form free radicals.

Of the thermally activatable polymerization initiators, preference isgiven to initiators with a decomposition temperature in the range from20 to 180° C., in particular from 50 to 90° C. Examples of suitablethermal initiators are inorganic peroxo compounds, such asperoxodisulfates (ammonium and preferably sodium peroxodisulfate),peroxosulfates, percarbonates and hydrogen peroxide; organic peroxocompounds, such as diacetyl peroxide, di-tert-butyl peroxide, diamylperoxide, dioctanoyl peroxide, didecanoyl peroxide, dilauroyl peroxide,dibenzoyl peroxide, bis(o-tolyl)peroxide, succinyl peroxide, tert-butylperacetate, tert-butyl permaleate, tert-butyl perisobutyrate, tert-butylperpivalate, tert-butyl peroctoate, tert-butyl perneodecanoate,tert-butyl perbenzoate, tert-butyl peroxide, tert-butyl hydroperoxide,cumene hydroperoxide, tert-butyl peroxy-2-ethylhexanoate and diisopropylperoxydicarbamate; azo compounds, such as 2,2′-azobisisobutyronitrile,2,2′-azobis(2-methylbutyronitrile) andazobis(2-amidopropane)dihydrochloride.

These initiators can be used in combination with reducing compounds asstarter/regulator systems. Examples of such reducing compounds which maybe mentioned are phosphorus-containing compounds, such as phosphorusacid, hypophosphites and phosphinates, sulfur-containing compounds, suchas sodium hydrogen sulfite, sodium sulfite and sodium formaldehydesulfoxylate, and hydrazine.

Examples of suitable photoinitiators are benzophenone, acetophenone,benzoin ether, benzyl dialkyl ketones and derivatives thereof.

Preferably, thermal initiators are used, preference being given toinorganic peroxo compounds, in particular sodium peroxodisulfate (sodiumpersulfate). It is particularly advantageous to use the peroxo compoundsin combination with sulfur-containing reducing agents, in particularsodium hydrogensulfite, as redox initiator system. If thisstarter/regulator system is used, copolymers are obtained which contain—SO₃ ⁻Na⁺ and/or —SO₄ ⁻Na⁺ as end groups and are characterized byparticular cleaning power and deposit-inhibiting action.

Alternatively, it is also possible to use phosphorus-containingstarter/regulator systems, e.g. hypophosphites/phosphinates.

The amounts of photoinitiator and/or starter/regulator system are to bematched to the substances used in each case. If, for example, thepreferred system of peroxodisulfate/hydrogensulfite is used, thenusually 2 to 6% by weight, preferably 3 to 5% by weight, ofperoxodisulfate and usually 5 to 30% by weight, preferably 5 to 10% byweight, of hydrogensulfate, are used, in each case based on the monomers(a), (b) and (c).

If desired, it is also possible to use polymerization regulators.Suitable compounds are those known to the person skilled in the art,e.g. sulfur compounds, such as mercaptoethanol, 2-ethylhexylthioglycolate, thioglycolic acid and dodecyl mercaptan. Ifpolymerization regulators are used, their use amount is usually 0.1 to15% by weight, preferably 0.1 to 5% by weight and particularlypreferably 0.1 to 2.5% by weight, based on the monomers (a), (b) and(c).

The polymerization temperature is usually 30 to 200° C., preferably 50to 150° C. and particularly preferably 80 to 120° C.

The polymerization can be carried out under atmospheric pressure,although it is preferably carried out in a closed system under theautogenous pressure which develops.

During the preparation of the copolymers to be used according to theinvention, the monomers (a), (b) and (c) can be used as they are,although it is also possible to use reaction mixtures which are producedduring the preparation of the monomers (c). Thus, for example, insteadof methoxypolyethylene glycol methacrylate, the monomer mixture whichforms during the esterification of polyethylene glycol monomethyl etherwith an excess of methacrylic acid can be used. Advantageously, theesterification can also be carried out in situ in the polymerizationmixture by combining (1) acrylic acid, (2) a mixture of methacrylic acidand polyethylene glycol monomethyl ether and (3) free radical startersin parallel. Where appropriate, a catalyst necessary for theesterification, such as methanesulfonic acid or p-toluenesulfonic acidcan additionally be used here.

The copolymers to be used according to the invention can also beprepared by polymer-analogous reaction, e.g. by reaction of an acrylicacid/methacrylic acid copolymer with polyalkylene glycol monoalkylether. Preference is, however, given to free radical copolymerization ofthe monomers.

If desired for the application, the aqueous solutions produced duringthe preparation of the carboxylic acid group-containing copolymers to beused according to the invention can be neutralized or partiallyneutralized by adding base, in particular sodium hydroxide solution,i.e. be adjusted to a pH in the range from 4-8, preferably 4.5-7.5.

The copolymers used according to the invention are highly suitable asadditive for detergents and cleaners.

They can particularly advantageously be used in machine dishwashingdetergents. They are characterized primarily by their deposit-inhibitingaction both toward inorganic and also organic deposits. In particular,deposits which are caused by the other constituents of the cleaningformulation, such as deposits of calcium and magnesium phosphate,calcium and magnesium silicate and calcium and magnesium phosphonate,and deposits which originate from the soil constituents of the washliquor, such as fat, protein and starch deposits should be mentioned.The copolymers used according to the invention thereby also increase thecleaning power of the dishwashing detergent. In addition, even in lowconcentrations, they favor run-off of the water from the ware, meaningthat the amount of rinse-aid surfactants in the dishwashing detergentcan be reduced. If the sulfonic acid group-containing copolymers areused, particularly clear glassware and gleaming metal cutlery items areobtained, particularly when the dishwasher is operated withoutregenerating salt to soften the water. The sulfonic acidgroup-containing copolymers can therefore be used not only in 2 in 1detergents, but also in 3 in 1 detergents.

The copolymers used according to the invention can be used directly inthe form of the aqueous solutions produced during the preparation, andalso in dried form obtained, for example, by spray drying, fluidizedspray drying, drum drying or freeze drying. The detergents and cleanersaccording to the invention can correspondingly be prepared in solid orin liquid form, e.g. as powders, granulates, extrudates, tablets,liquids or gels.

EXAMPLES

A) Preparation of Copolymers Containing Alkylene Oxide Units

Example 1

In a reactor fitted with nitrogen inlet, reflux condenser and meteringdevice, a mixture of 619 g of distilled water and 2.2 g of phosphorusacid was heated to an internal temperature of 100° C. with theintroduction of nitrogen and stirring. Then, in parallel, (1) a mixtureof 123.3 g of acrylic acid and 368.5 g of distilled water, (2) a mixtureof 18.4 g of sodium peroxodisulfate and 164.6 g of distilled water, (3)a mixture of 72.0 g of water, 49.1 g of methacrylic acid and 166.9 g ofmethoxypolyethylene glycol methacrylate (M_(w)=1100) and (4) 46 g of a40% strength by weight aqueous sodium hydrogensulfite solution wereadded continuously over 5 h. Following after-stirring for two hours at100° C., the reaction mixture was cooled to room temperature andadjusted to a pH of 7.2 by adding 190 g of 50% strength by weight sodiumhydroxide solution.

A slightly yellowish, clear solution of a copolymer with a solidscontent of 25.7% by weight and a K value of 27.2 (1%. strength by eightaqueous solution, 25° C.) was obtained.

Example 2

In the reactor from example 1, a mixture of 221.6 g of distilled waterand 1.1 g of phosphorus acid was heated to an internal temperature of100° C. with the introduction of nitrogen and stirring. Then, inparallel, (1) a mixture of 38.6 g of acrylic acid and 231.0 g ofdistilled water, (2) a mixture of 29.6 g of toluene,, 27.7 g ofmethacrylic acid and 116.6 g of methoxypolyethylene glycol methacrylate(M_(w)=1100) and (3) 68.6 g of a 40% strength by weight aqueous sodiumhydrogensulfite solution were added continuously over 5 h. In parallelto this, a mixture of 9.1 g of sodium peroxodisulfate and 82.3 g ofdistilled water was added over 5.25 h. In parallel to these feeds, amixture of water and toluene was continuously distilled off, and thewater was returned to the reaction (azeotropic removal of the toluene).

Following after-stirring for one hour at 100° C., the reaction mixturewas cooled to room temperature and adjusted to a pH of 7.2 by adding 85g of 50% strength by weight sodium hydroxide solution.

A clear polymer solution with a solids content of 28.8% by weight and aK value of 28.9 (1% strength by weight aqueous solution, 25° C.) wasobtained.

B) Use of Copolymers Containing Alkylene Oxide Units in DishwashingDetergents

To test their deposit-inhibiting action, the copolymers obtained wereused together with a dishwashing detergent formulation having thefollowing composition:

-   50% by weight sodium tripolyphosphate (Na₃P₃O₁₀.6 H₂O)-   27% by weight sodium carbonate-   3% by weight sodium disilicate (x Na₂O.y SiO₂; x/y=2.65; 80%    strength)-   6% by weight sodium percarbonate (Na₂CO₃.1.5 H₂O₂)-   2% by weight tetraacetylenediamine (TAED)-   2% by weight low-foam nonionic surfactant based on fatty alcohol    alkoxylates-   3% by weight sodium chloride-   5% by weight sodium sulfate-   2% by weight polyacrylic acid sodium salt (M_(w) 8 000)

The test was carried out under the following washing conditions withoutthe addition of ballast soiling, with neither rinse aid nor regeneratingsalt being used: Washing conditions: Dishwasher: Miele G 686 SC Washprograms: 2 wash programs at 55° C. normal (without prewash) Ware:knives (WMF Tafelmesser Berlin, Monoblock) and barrel-shaped glassbeakers (Matador, Ruhr Kristall) Dishwashing detergent: 21 g Copolymer:4.2 g Clear-rinse temperature: 65° C. Water hardness: 25° Germanhardness

The ware was evaluated 18 h after washing by visual assessment in ablack-painted light box with halogen spotlight and pinhole diaphragmusing a grading scale from 10 (very good) to 1 (very poor). The highestgrade 10 corresponds here to surfaces free from deposits and drops, fromgrades <5, deposits and drops are visible in normal room lighting, andare therefore regarded as troublesome.

The test results obtained are listed in the table below. TABLEEvaluation (grade) Copolymer from Ex. Knives Glasses 1 8.0 7.7 2 6.2 7.5— 4.0 4.0

1. A detergent or a cleaner which comprises one or more copolymerscomprising alkylene oxide units which comprise (a) 50 to 93 mol % ofacrylic acid and/or a water-soluble salt of acrylic acid, (b) 5 to 30mol % of methacrylic acid and/or a water-soluble salt of methacrylicacid and (c) 2 to 20 mol % of at least one nonionic monomer of formula I

wherein: R¹ is hydrogen or methyl; R² is a chemical bond or unbranchedor branched C₁-C₆-alkylene; R³ are identical or different unbranched orbranched C₂-C₄-alkylene radicals; R⁴ is unbranched or branchedC₁-C₆-alkyl; n is 3 to 50, in random or block copolymerized form.
 2. Thedetergent or cleaner as claimed in claim 1, wherein said one or morecopolymers comprise 65 to 85 mol % of component (a), 10 to 25 mol % ofcomponent (b) and 5 to 15 mol % of component (c) in copolymerized form.3. The detergent or cleaner as claimed in claim 1, wherein said one ormore copolymers comprise 65 to 75 mol % of component (a), 15 to 25 mol %of component (b) and 5 to 10 mol % of component (c) in copolymerizedform.
 4. The detergent or cleaner as claimed in claim 1, wherein saidone or more copolymers comprise, as component (c), a nonionic monomer ofthe formula I wherein R¹ is methyl, R² is a chemical bond, R³ isC₂-C₃-alkylene, R⁴ is C₁-C₂-alkyl and n is 5 to 40, in copolymerizedform.
 5. The detergent or cleaner as claimed in claim 1, wherein saidone or more copolymers comprise, as component (c), a nonionic monomer ofthe formula I wherein R¹ is methyl, R² is a chemical bond, R³ isethylene, R⁴ is methyl and n is 10 to 30, in copolymerized form.
 6. Thedetergent or cleaner as claimed in claim 1, wherein said one or morecopolymers comprise —SO₃ ⁻Na⁺ and/or —SO₄ ⁻Na⁺ as end-groups. 7.(canceled)
 8. The detergent or cleaner as claimed in claim 1 whichcomprises said one or more copolymers as deposit-inhibiting additive. 9.The detergent or cleaner as claimed in claim 8, wherein said detergentis a machine dishwashing detergent.